1. Field of the Invention
The present invention relates to a piezoelectric film and the usage thereof.
2. Description of the Related Art
A perovskite composite oxide [(Na, Bi)1-x Bax] TiO3 (hereinafter, referred to as “NBT-BT”) has been recently researched and developed as a non-lead (lead-free) ferroelectric material.
US Pre-Grant Patent Application Publication No. 2013/0328974A1 discloses an NBT-BT film having a high polarization-disappearance temperature Td. In particular, US Pre-Grant Patent Application Publication No 2013/0328974A1 discloses that a (1-α) (Na, Bi, Ba) TiO3-αBiQO3 (Q=Fe, Co, Zn0.5Ti0.5, or Mg0.Ti0.5) layer formed on an NaxLa1−x+yNi1−yO3−x layer by RF magnetron sputtering under a temperature of 650 degrees Celsius has a polarization-disappearance temperature Td of approximately 180 degrees Celsius-250 degrees Celsius. The (1-α) (Na, Bi, Ba) TiO3-αBiQO3 layer has a (001) orientation only. The NaxLa1−x+yNi1−yO3−x layer is formed on a Pt film having a (111) orientation by an RF magnetron sputtering under a temperature of 300 degrees Celsius.
Journal of the American Ceramic Society 93 [4] (2010) 1108-1113 discloses a method for measuring a polarization-disappearance temperature Td.